Superheated Steam as Pretreatment to Reduce Oil Uptake During Deep-Fat

Frying of Chicken Nuggets

Julieta Rosete Hidalgo, María Elena Sosa Morales, Jorge F. Vélez Ruiz

Universidad de las Américas, Puebla, México

Stefan CenkowskiUniversity of Manitoba, Winnipeg, Canada

CSBE/SCGAB, Vancouver, BC, Jul 13-16, 2008

Why?The current proportion of children in America who are overweight have tripled since 1980.  

Approximately 65% of people are overweight.  The data also show that 31% of people now suffer from Obesity, compared with only 23% in 1994.

According to American statistics, obesity increases a risk of a number of life threatening conditions, such as diabetes, heart disease, stroke, high blood pressure, and some types of cancer.

Overall objective• To lower the oil uptake in deep-fat frying of chicken

nuggets by pre-treating them with superheated steam prior to frying

• Specific objectives• compare the final moisture content, • oil uptake, and • the quality attributes (color, texture, density, thermal

conductivity)

Materials and Methods

Frying of nuggets at140 and 160°C, 3 min SS temperature: 110 and 140 ºC

Duration of treatment: 3 y 5 min SS flow rate: 11.23 kg/h at 5 kPa

Methods

Temperature: Thermocouples type J

Moisture determination: 110°C, 24 h (AOAC, 1995)

Oil content: petroleum-ether extraction 6 h, 78 min

Thermal conductivity: Thermal properties analyzer (KY-2, Decagon Devices)

Density: mass volume displacement method

Texture: Penetration 15%, 5mm/s with a 2 mm dia. probe (Texture Analyzer TA- TX2)

Color: Hunter Lab values at two locations (Chroma Meter CR-400 (Minolta)

Statistical analysis: analysis of variance (ANOVA) and means separated using Tukey’s method at 0.05 significance level (Minitab)

Methods

Conditions used in combined SHS and deep-fat frying of chicken nuggets

VariableConditions

Control 1 2 3 4

Steam temperature,°C - 110 110 140 140

SS treatment time (min)

- 3 5 3 5

Frying time,160°C (s) 180 100 60 70 50

Moisture loss during deep-fat frying of chicken nuggets at 160C

30

40

50

60

70

80

0 1 2 3

Frying time (min)

Moi

stur

e co

nten

t (%

wb)

Core

Crust

Oil gain during deep-fat frying of chicken nuggets at 160C

0

5

10

15

20

25

30

0 1 2 3

Frying time (min)

Oil

co

nte

nt

(% w

b)

Core

Crust

Temperature changes during deep-fat frying of chicken nuggets for a control sample

0

10

20

30

40

50

60

70

80

0 15 30 45 60 75 90 105 120 135 150 165 180

Frying time (s)T

em

pera

ture

(°C

)

Coretemperature

0

20

40

60

80

100

120

140

160

0 30 60 90 120 150 180 210 240 270 300

SSH treatment time (s)

Tem

pera

ture

(°C

)

SSH chamber - Cond1&2 Core - Cond 1Core - Cond 2SSH chamber - Cond 3&4Core - Cond 3Core - Cond 4

…and for SS treatment with conditions 1- 4

The penetration force measured for chicken nuggets pretreated with SS and fried (conditions 1- 4) vs control

1.58

1.09

1.38

1.13

1.45

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

Force (N)

sistemas

Control

Condition 1

Condition 2

Condition 3

Condition 4

Control 1 2 3 4

Density of fried and SS pre-treated nuggets as compared to control

890.05980.05

892.72944.98 890.56

0

300

600

900

Density

(kg/m3)

sistemas

ControlCondition 1Condition 2Condition 3Condition 4

Control 1 2 3 4

Conclusions

In comparison to 3-min deep-fat frying, a reduced oil uptake was obtained in the core (2.5% wb) and in the crust (16.7% wb) when SS treated at110C for 5 min followed by 1-min frying but resulted in higher moisture content of the core (1.7-3.7% wb) and the crust (13.5-18.8% wb).

No change: in density, thermal conductivity Similar texture and more yellowish color